Heterocyclic compounds and antitumor drugs containing the same as the active ingredient

ABSTRACT

The present invention relates to heterocyclic compounds represented by the formula I  
                 
 
wherein X represents nitrogen atom or CH; R 1  represents halogen atom or hydroxyl; R 2  represents hydrogen atom, hydroxyl or amino; R 3  represents morpholino (which may be substituted with one or two C 1 -C 6  alkyl), pyrrolidinyl (which may be substituted with hydroxy C 1 -C 6  alkyl) or NR 6 R 7  [R 6  represents C 1 -C 6  alkyl and R 7  represents piperidinyl (which may be substituted with C 1 -C 6  alkyl)]; R 4  and R 5  each represents hydrogen atom or C 1 -C 6  alkyl, with the proviso that R 2  is hydrogen atom and R 3  is pyrrolidinyl (which may be substituted with hydroxy C 1 -C 6  alkyl) when R 1  is hydroxyl

TECHNICAL FIELD

The present invention relates to heterocyclic compounds represented bythe formula I or pharmaceutically acceptable salts thereof and antitumoragents containing the heterocyclic compounds as effective components:

wherein X represents nitrogen atom or CH; R₁ represents halogen atom orhydroxyl; R₂ represents hydrogen atom, hydroxyl or amino; R₃ representsmorpholino (which may be substituted with one or two C₁-C₆ alkyl),pyrrolidinyl (which may be substituted with hydroxy C₁-C₆ alkyl) orNR₆R₇ [R₆ represents C₁-C₆ alkyl and R₇ represents piperidinyl (whichmay be substituted with C₁-C₆ alkyl)]; R₄ and R₅ each represent hydrogenatom or C₁-C₆ alkyl, with the proviso that R₂ is hydrogen atom and R₃ ispyrrolidinyl (which may be substituted with hydroxy C₁-C₆ alkyl) when R₁is hydroxyl.

BACKGROUND ART

s-Triazine (1,3,5-triazine) and pyrimidine derivatives have beenresearched in the fields of synthetic resins, synthetic fibers, dyes andagricultural chemicals and a number of such compounds have beensynthesized. In the field of pharmaceuticals, researches have been madewith respect to antitumor, anti-inflammatory, analgesic, antispasmodicactivities and the like. Especially, hexamethylmelamine (HMM) iswell-known which has been developed as analogue of antitumor agenttriethylenemelamine (TEM) [see, for example, B. L. Johnson et al.Cancer, 42: 2157-2161 (1978)].

TEM is known as alkylating agent and is an s-triazine derivative havingcytotoxic antitumor activity. HMM has been marketed in Europe under theindications for the treatment of ovarian and small cell lung cancers,and its action on solid cancers have attractive.

Among the s-triazine derivatives, imidazolyl-s-triazine derivativeswhich exhibit cytotoxic and selective aromatase inhibitory activitieshave been proposed as medicine for estrogen-dependent diseases such asendometriosis, multicystic ovarium, mastosis, endometrium carcinoma andbreast cancer (see, for example, PCT international publicationWO93/17009).

In order to expand antitumor activities of HMM and to decrease aromataseinhibitory activities of imidazolyl-s-triazine derivatives, we, theinventors, carried out intensive studies to find out s-triazine andpyrimidine derivatives with substitution of benzimidazole (see, forexample, PCT international publications WO99/05138 and WO00/43385).

However, there is still room for improvement on HMM with respect to itsantitumor spectrum and intensity of antitumor activities against solidcancers in B. L. Johnson et al. Cancer, 42: 2157-2161 (1978). As toimidazolyl-s-triazine derivatives as disclosed in WO093/17009, they arelimitative in application since they exhibit considerably higheraromatase inhibitory activities than their cytotoxic activities andapplication of them to cancerous patients other than those who sufferfrom estrogen-dependent diseases may lead to development of secondaryeffects such as menstrual disorders due to lack of estrogen. There arestill, therefore, strong demands on medicines with no aromataseinhibitory activities and effective for solid cancers.

Even the compounds as disclosed in PCT international publicationsWO99/05138 and WO00/43385 have not been satisfactory with respect totheir anti-tumor activities.

SUMMARY OF THE INVENTION

We, the inventors, further developed the studies to find out thatheterocyclic compounds with specific substituents at position 2 ofbenzimidazole ring and represented by the formula I exhibit by farimproved antitumor activities, thus completing the present invention.

The terms used for definition of letters in the formula I, by which theheterocyclic compounds of the present invention are represented, will bedefined and exemplified in the following.

The term “C₁-C₆” refers to a group having 1 to 6 carbon atoms unlessotherwise indicated.

The “C₁-C₆ alkyl” refers to a straight- or branched-chain alkyl groupsuch as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl,n-pentyl or n-hexyl.

The “hydroxy C₁-C₆ alkyl” refers to the above-mentioned “C₁-C₆ alkyl”with any of the carbon atoms coupled to hydroxy group.

The “halogen atom” refers to fluorine, chlorine, bromine or iodine.

The compounds according to the present invention may be as follows,though the present invention is not limited to these compounds.

-   2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-(2,2-dimethylmorpholino)-6-morpholino-1,3,5-triazine-   2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-[methyl(1-methylpiperidin-4-yl)amino]-6-morpholino-1,3,5-triazine-   2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholino-1,3,5-triazine-   2-(4-chloro-2-difluoromethyl-5-hydroxybenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine-   2-(4-chloro-2-difluoromethyl-5-hydroxybenzimidazol-1-yl)-4-(2,2-dimethylmorpholino)-6-morpholino-1,3,5-triazine-   2-(2-difluoromethyl-4-hydroxybenzimidazol-1-yl)-4-(2-hydroxylmethylpyrrolidin-1-yl)-6-morpholino-1,3,5-triazine-   2-(2-difluoromethyl-4-hydroxybenzimidazol-1-yl)-4-(2-hydroxylmethylpyrrolidin-1-yl)-6-morpholinopyrimidine-   2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-(2,2-dimethylmorpholino)-6-morpholinopyrimidine-   2-(4-chloro-2-difluoromethyl-5-hydroxybezimidazol-1-yl)-4,6-dimorpholinopyrimidine-   2-(4-chloro-2-difluoromethyl-5-hydroxybenzimidazol-1-yl)-4-(2,2-dimethylmorpholino)-6-morpholinopyrimidine-   2-(4-bromo-2-difluoromethylbenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine-   2-(4-fluoro-2-difluoromethylbenzimidazbl-1-yl)-4,6-dimorpholino-1,3,5-triazine

The compounds of the present invention may have asymmetric carbon atomsin the structure. It is to be understood that isomers due to suchasymmetric carbon atom or combination (racemate) of any of the isomersare included in the category of the compounds according to the presentinvention.

Furthermore, the compounds of the present invention may be in the formof pharmaceutically acceptable acid addition salts. The appropriate acidaddition salts which can be used include, for example, inorganic saltssuch as hydrochloride, sulfate, hydrobromide, nitrate and phosphate aswell as organic acid salts such as acetate, oxalate, propionate,glycolate, lactate, pyruvate, malonate, succinate, maleate, fumarate,malate, tartarate, citrate, benzoate, cinnamate, methanesulfonate,benzenesulfonate, p-toluenesulfonate and salicylate.

Production Processes

The compounds of the present invention represented by the formula I maybe prepared by, as shown in the following reaction formula, reactingcyanuric chloride or 2,4,6-trichloropyrimidine (compound II) as startingmaterial with benzimidazole compound (compound V), morpholine compound(compound VI) and R₃H (compound VII) successively in the order named.

wherein R₁, R₂, R₃, R₄, R₅ and X are as defined above and R′ representshydrogen atom, amino or tert-butyldimethyl-silyloxy.

Next, the respective production processes will be described.

1) Production Process (i) of Intermediate III:

wherein R₁, R′ and X are as defined above.

In a solvent, cyanuric chloride or 2,4,6-trichloro-pyrimidine (compoundII) is reacted with benzimidazole compound (compound V) in the presenceof hydrogen chloride trapping agent to obtain the intermediate III.

The hydrogen chloride trapping agent used in this reaction may be, forexample, sodium hydroxide, potassium hydroxide, sodium carbonate,potassium carbonate, triethylamine or pyridine. The solvent used may beacetone, toluene, hexane, xylene, dioxane, tetrahydrofuran ordichloroethane or N,N-dimethylformamide (DMF).

In this reaction, 0.5-1.2 moles of the compound V is used per mole ofthe compound II in the presence of 0.5-2 moles of the hydrogen chloridetrapping agent. The reaction is made at the temperature of −15° C.-−5°C. for 0.5-2 hours, and further at the room temperature for 5-50 hours.

It is to be noted that the compound V may be also used as the hydrogenchloride trapping agent.

2) Production Process (ii) of Intermediate IV

wherein R₁, R₄, R₅, R′ and X are as defined above.

In the solvent, the intermediate III obtained in the above-mentionedproduction process (i) is reacted with morpholine compound (compound VI)in the presence of hydrogen chloride trapping agent to obtain theintermediate IV. The hydrogen chloride trapping agent used in thisreaction may be the same as those in the above-mentioned productionprocess (i). The solvent used may be DNF, acetone, toluene, xylene,dichloroethane or dichloromethane.

In this reaction, 0.5-1.2 moles of the compound VI is used per mole ofthe intermediate III and in the presence of 0.5-3 moles of the hydrogenchloride trapping agent. The reaction is made at the temperature of −5°C.-0° C. for 0.5-3 hours, and further at the room temperature for 5-50hours.

It is to be noted that the compound VI may be also used as the hydrogenchloride trapping agent.

3) Production Process (iii) of the Compound I

wherein R₁, R₂, R₃, R₄, R₅, R′ and X are as defined above.

In the solvent, the intermediate IV obtained in the above-mentionedproduction process (ii) is reacted with R₃H (compound VII) in thepresence of hydrogen chloride trapping agent to obtain the compound Iaccording to the present invention.

The hydrogen chloride trapping agent used in this reaction may be thesame as those in the above-mentioned production process (i). The solventused may be DMF, dimethyl sulfoxide (DMSO), xylene or dichloroethane.

In this reaction, 1-5 moles of R₃H (compound VII) is used per mole ofthe intermediate IV at the temperature between room temperature and 140°C. for 0.1-16 hours. In the case of the reaction in the presence of thehydrogen chloride trapping agent, 1-5 moles of the hydrogen chloridetrapping agent is used per mole of the intermediate IV. It is to benoted that the compound VII may be also used as the hydrogen chloridetrapping agent.

In such production of the compound I and when the compounds VI and VIIare the same, the production processes (ii) and (iii) may be carried outin a single step to obtain the compound I. In this case, the reactionconditions are as mentioned in the above with respect to the productionprocess (ii) except that 2-10 moles of the compound VI or VII is usedper mole of the compound III and that the reaction is made at thetemperature of −10° C.-5° C. for 0.1-5 hours, and further at thetemperature between room temperature and 120° C. for 3-50 hours.

When the compound V, VI or VII used in the production process (i), (ii)or (iii) has lower reactivity, it is preferable that the productionprocess is carried out after treatment with sodium hydride. In the caseof sodium hydride being used, 1.0-1.2 moles of sodium hydride is usedper mole of the starting material (compound II, III or IV) in theproduction process.

When R₁ or R₂ is hydroxyl, the reaction is carried out, usingbenzimidazole compound with hydroxy protected by alkylsilyl group suchas tert-butyldimethylsilyl according to ordinary method; in a finalstep, the protective group is removed to obtain the aimed compound. Thecompounds according to the present invention where R₁ is halogen atomand R₂ is hydroxyl may be obtained by halogenating, according toordinary method, the compounds I similarly obtained in the above methodand where R₁ is hydrogen atom and R₂ is hydroxyl.

The above-mentioned production processes (i), (ii) and (iii) may becarried out in any exchanged order. In such a case, the reactionconditions may be varied to an extent obvious to ordinary experts in theart.

The resultant products in the above-mentioned respective productionprocesses may be separated and purified, as needs demand, by ordinarymethod such as extraction, condensation, neutralization, filtration,re-crystallization or column chromatography.

Acid-addition salts of the compounds I of the present invention may beprepared according to various methods well-known in the art. Theappropriate acids used include, for example, inorganic acids such ashydrochloric, sulfuric, hydrobromic, nitric or phosphoric acid, andorganic acids such as acetic, oxalic, propionic, glycolic, lactic,pyruvic, malonic, succinic, maleic, fumaric, malic, tartaric, citric,benzoic, cinnamic, methanesulfonic, benzenesulfonic, p-toluenesulfonicor salicylic acid.

Next, antitumor activities of the compounds I of the present inventionwill be described. Numbers of the tested compounds in the tests 1 and 2correspond to those in Examples referred to hereinafter.

Comparative compounds used were the following s-triazine-seriesantitumor agents or medicines for estrogen-dependent diseases:

Compound A:2-(benzimidazol-1-yl)-4-(trans-2,3-dimethylmorpholino)-6-morpholinopyrimidine(a typical compound disclosed in the international publicationWO99/05138)

Compound B:2-(2-methylbenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine (a typicalcompound disclosed in the international publication WO99/05138)

Compound C: 2-(imidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine (typicalcompound disclosed in the international publication WO93/17009)

Compound D: hexamethylmelamine (HMM)

Test 1

Used in the test were MCF-7 cells which were established from humanbreast cancer and were cultured routinely under the conditions of 37° C.and 5% CO₂, in MEM medium supplemented with 10% fetal calf serum, 25 mMof HEPES and 0.1 mg/ml of kanamycin. The MCF-7 cells in a logarithmicgrowth phase were treated with trypsin/EDTA to prepare single cellsuspension adjusted to 4.0×10⁴ cells/ml in MEM medium (supplemented with10% fetal calf serum, 25 mM of HEPES and 0.1 mg/ml of kanamycin). Testcompounds were dissolved in DMSO and diluted with RPMI 1640 medium(supplemented with 10% fetal calf serum, 25 mM of HEPES and 0.1 mg/ml ofkanamycin) to a concentration of 2.0×10⁻⁹−2.0×10⁻⁴ M.

The cell suspension was filled in a 96-wells microplate at a rate of 0.1ml per well and was cultured for 24 hours so as to make the cellsadhered to the microplate. Then, it was added with 0.1 ml of the samplesolution and cultured at 37° C. for 72 hours in 5% CO₂.

50% Growth inhibition concentrations (GI₅₀ μM) were calculated fromgrowth inhibitions at various sample concentrations. The results are asshown in Table 1. TABLE 1 test compound GI₅₀ (μM) compound 1 0.07compound 2 0.08 compound 3 0.27 compound 5 0.06 compound 6 0.08 compoundA 2.2 compound B 3.7 compound C 20 compound D >100

The above test results clearly revealed that the compounds of thepresent invention exhibit by far superior antitumor activities on humanbreast cancer cells than the known comparative compounds A, B, C and D.

The compounds of the present invention were also effective in vitrotests using human non small cell lung cancer cells and human coloniccancer cells and therefore positively expected is application of thecompounds according to the present invention on treatment of varioushuman solid cancers.

Test 2

Mutant BALB/c nude mice were used for routine culture of 2-mm-squarepiece of human colonic cancer WiDr which was transplanted subcutaneouslyinto left breast of each of the mice. The mice were separated fortesting into groups each of five mice at the time of the tumor in itslogarithmic growth phase. The samples prepared by dissolving testcompounds in physiological saline solution or suspending them in 1%hydroxypropyl cellulose (HPC), using an agate mortar, wereintraperitoneally administered at a rate of 200 mg/kg, once a day andsix times a week in total, for two weeks. Major and minor axes of thetumor mass were measured on a daily basis to calculate tumor volume. Thetumor volume at each measured day was divided by that at the start dayof the sample administration to calculate relative tumor growth rate;and the relative tumor growth rate of the treated groups (T) and that ofthe control group (C) were used to calculate T/C (%) Cases where T/C (%)of the last day was less than 50% and U-assay of Mann-Whitney revealedsignificant difference with one-sided risk rate of 1% were judged to beeffective (+). As a result, the compound according to the presentinvention was effective whereas the comparative compound A wasineffective.

Next, description will be made on ways of administration, formulationsand dosage of the compounds of the present invention where they areapplied to mammals, especially to human.

The compounds of the present invention may be administered orally orparenterally. In oral administration, the compounds may be in theformulation of tablets, coated tablets, powders, granules, capsules,microcapsules, syrups and the like; and in parenteral administration, inthe formulation of injections which may include soluble freeze-dryingformulation, suppositories and the like. In the preparation of theseformulations, pharmaceutically acceptable excipient, binders,lubricants, disintegrators, suspensions, emulsifiers, antiseptics,stabilizers and dispersing agents, for example, lactose, sucrose,starch, dextrin, crystalline cellulose, kaolin, calcium carbonate, talc,magnesium stearate, distilled water and physiological saline solutionmay be used.

The dosage for humans may depend on the condition of the disease to betreated, the age and weight of the patient and the like. A daily dosagefor an adult may be in the range of from 100 to 1,000 mg and may begiven in divided doses 2 or 3 times a day.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, the present invention is more specifically illustrated withreference to the following Examples of the compounds. It is to be,however, noted that the present invention is not limited to theseExamples.

EXAMPLE 12-(2-difluoromethyl-4-hydroxybenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholinopyrimidine(Compound 1)

(1) 1.49 g (5.0 mmol) of4-tert-butyldimethylsilyloxy-2-difluoromethylbenzimidazole dissolved inDMF (10 ml) was added with a solution of 2,4,6-trichloropyrimidine (0.91g, 5.0 mmol) at room temperature, and further added with potassiumcarbonate (0.55 g) and stirred for 5 hours. The reaction solution waspoured into water and extracted with ethyl acetate several times, washedwith saturated saline solution and dried over anhydrous magnesiumsulfate. The solvent was removed under reduced pressure and the residuewas purified by silica gel column chromatography (n-hexane:ethylacetate=8:1) to obtain 1.12 g (yield: 50%) of2-(4-tert-butyldimethylsilyloxy-2-difluoromethylbenzimidazol-1-yl)-4,6-dichloropyrimidine.

(2) 386 mg (0.87 mmol) of the obtained2-(4-tert-butyldimethylsilyloxy-2-difluoromethylbenzimidazol-1-yl)-4,6-dichloropyrimidinedissolved in DMF (6 ml) was added with 2-pyrrolidinmethanol (0.13 ml,1.3 mmol) at room temperature, further added with potassium carbonate(179 mg) and stirred at room temperature for 30 minutes. The reactionsolution was poured into water and extracted several times with ethylacetate, washed with saturated saline solution and dried over anhydrousmagnesium sulfate. The solvent was removed under the reduced pressureand the residue was purified by silica gel column chromatography(n-hexane:ethyl acetate=1 :1) to obtain 291 mg (yield: 64%) of2-(4-tert-butyldimethylsilyloxy-2-difluoromethyl-benzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-chloropyrimidine.

(3) 281 mg (0.54 mmol) of the obtained2-(4-tert-butyldimethylsilyloxy-2-difluoromethylbenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-chloropyrimidineadded with morpholine (4.4 g, 50 mmol) was stirred at room temperaturefor 9 hours. The reaction solution was poured into water, extractedseveral times with ethyl acetate, washed with saturated saline solutionand dried over anhydrous magnesium sulfate. The solvent was removedunder the reduced pressure and the residue was purified by silica gelcolumn chromatography (n-hexane:ethyl acetate=2:3) to obtain 216 mg(yield: 72%) of2-(4-tert-butyldimethylsilyloxy-2-difluoromethylbenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholinopyrimidine.

213 mg (0.38 mmol) of2-(4-tert-butyldimethyl-silyloxy-2-difluoromethylbenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholinopyrimidinedissolved in anhydrous THF (7 ml) was added withtetra-n-butylammoniumfluoride (0.4 ml, lM THF solution) at roomtemperature and stirred for 30 minutes. The reaction solution was addedwith water, extracted several times with ethyl acetate, washed withsaturated saline solution and dried over anhydrous magnesium sulfate.The solvent was removed under the reduced pressure and the residue waspurified by silica gel column chromatography (n-hexane ethylacetate=1:4) to obtain 101 mg (yield: 60%) of the titled compound ascolorless crystals.

Melting point: 195-198° C.

NMR (CDCl₃) δ: 2.0-2.1 (4H, m), 3.4-4.0 (12H, m), 4.0-4.1 (1H, m),4.3-4.4 (1H, m), 5.36 (1H, s), 6.85 (1H, d, J=8 Hz), 7.28 (1H, t, J=8Hz), 7.58 (1H, brs), 7.58 (1H, t, J=54 Hz), 7.73 (1H, d, J=8 Hz)

MS m/z: 446(M⁺)

EXAMPLE 22-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-(2,2-dimethylmorpholino)-6-morpholino-1,3,5-triazine(Compound 2)

(1) 500 mg (2.3 mmol) of 6-amino-4-chloro-2-difluoromethylbenzimidazoledissolved in acetone (50 ml) was added with2,4-dichloro-6-morpholino-1,3,5-triazine (542 mg, 2.3 mmol) at −15° C.and further added with potassium carbonate (500 mg). The reactionmixture was gradually raised in temperature into room temperature andstirred at room temperature for 5 hours. The solvent was removed underthe reduced pressure and the residue was purified by silica gel columnchromatography (n-hexane ethyl acetate=1:4) to obtain 272 mg (yield:28%) of2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-chloro-6-morpholino-1,3,5-triazine.

(2) 150 mg (0.36 mmol) of the obtained2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-chloro-6-morpholino-1,3,5-triazinedissolved in DMF (6 ml) was added with 2,2-dimethylmorpholinehydrochloride (150 mg, 1.0 mmol) at −15° C. and further added withpotassium carbonate (500 mg). The reaction mixture was stirred at roomtemperature overnight. The reaction solution was poured into water,extracted several times with ethyl acetate, washed with saturated salinesolution and dried over anhydrous magnesium sulfate. The solvent wasremoved under the reduced pressure and the residue was purified bysilica gel column chromatography (n-hexane:ethyl acetate 1:2) to obtain130 mg (yield: 73%) of the titled compound as colorless crystals.

Melting point: 238° C. (decomp.)

NMR (CDCl₃) δ: 1.27 (6H, s), 3.68 (2H, s), 3.7-3.9 (12H, m), 6.82 (1H,d, J=2.3 Hz), 7.42 (1H, dt, J=9.6 Hz, J=53 Hz), 7.50 (1H, d, J=2.3 Hz)

MS m/z: 494(M⁺)

In accordance with the procedure of the Example 2, the followingcompounds were prepared from the corresponding starting materials.

-   2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholino-1,3,5-triazine    (compound 3)

Melting point: 256° C. (decomp.)

NMR (CD₃OD-CDCl₃ (1:1)) δ: 1.9-2.2 (4H, m), 3.68 (2H, s), 3.5-4.0 (1H,m), 4.39 (1H, brs), 6.84 (1H, d, J=2.1 Hz) 7.58 (1H, t, J=53 Hz), 7.64(1H, d, J=2.1 Hz)

MS m/z:480(M⁺)

-   2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-[methyl(1-methylpiperidine-4-yl)amino]-6-morpholino-1,3,5-triazine    (compound 4)

Melting point: :194° C. (decomp.)

NMR (CD₃OD-CDCl₃ (1:1)) δ: 1.3-1.5 (2H, m), 1.8-2.1 (4H, m), 2.35 (3H,s), 2.9-3.2 (3H, m), 3.21 (3H, s), 3.5-3.8 (8H, m), 6.84 (1H, d, J=2.2Hz), 7.49 (1H, t, J=53 Hz), 7.80 (1H, d, J=2.2 Hz)

MS m/z:507(M⁺)

-   2-(2-difluoromethyl-4-hydroxybenzimidazol-1-yl)-4-(2-hydroxymetylpyrrolidin-1-yl)-6-morpholino-1,3,5-triazine    (compound 5)

Melting point: :245° C. (decomp.)

NMR (CDCl₃) δ: 1.9-2.1 (4H, m), 3.5-4.0 (12H, m), 4.7-4.8 (1H, m),5.1-5.3 (1H, m), 6.89 (1H, d, J=9 Hz), 7.30 (1H, t, J=9 Hz), 7.50 (1H,brs), 7.55 (1H, t, J=54 Hz), 7.83 (1H, d, J=9 Hz)

MS m/z:447(M⁺)

-   2-(2-difluoromethyl-5-hydroxybenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine

Melting point: >250° C.

NMR (CDCl₃) δ: 3.8-4.0 (16H, m), 7.01 (1H, d, J=9 Hz), 7.30 (1H,s), 7.54(1H, t, J=53 Hz), 8.19 (1H, d, J=9 Hz)

MS m/z: 433(M⁺)

EXAMPLE 32-(4-chloro-2-difluoromethyl-5-hydroxybenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine(compound 6)

In accordance with the procedure of the Example 2, 433 mg (1.00 mmol) of2-(2-difluoromethyl-5-hydroxybenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazinewas obtained. 433 mg (1.00 mmol) of the obtained compound dissolved inchloroform (10 ml) was added with N-chlorosuccinimido (400 mg, 3.0 mmol)and stirred at 60° C. for 1 hour. The reaction solution was poured intowater and extracted several times with chloroform, washed with saturatedsaline solution and dried over anhydrous magnesium sulfate. The solventwas removed under the reduced pressure and the residue was purified bysilica gel column chromatography (chloroform:methanol=99:1) to obtain189 mg (yield: 44%) of the titled compound as colorless crystals.

Melting point: >250° C.

NMR (CDCl₃) δ: 3.7-3.9 (16H, m), 5.63 (1H, s), 7.15 (1H, d, J=9 Hz),7.51 (1H, t, J=53 Hz), 8.14 (1H, d, J=9 Hz)

MS m/z: 467(M⁺)

INDUSTRIAL APPLICABILITY

The compounds of the present invention exhibit apparently by far strongantitumor activities with no aromatase inhibitory activities incomparison with conventional s-triazine and pyrimidine derivatives andcan be applied to treatment on solid cancers.

1. A heterocyclic compound represented by the formula I or apharmaceutically acceptable salt thereof:

wherein X represents nitrogen atom or CH; R₁ represents halogen atom orhydroxyl; R₂ represents hydrogen atom, hydroxyl or amino; R₃ representsmorpholino (which may be substituted with one or two C₁-C₆ alkyl),pyrrolidinyl (which may be substituted with hydroxy C₁-C₆ alkyl), NR₆R₇[R₆ represents C₁-C₆ alkyl and R₇ represents piperidinyl (which may besubstituted with C₁-C₆ alkyl)], R₄ and R₅ each represent hydrogen atomor C₁-C₆ alkyl, with the proviso that R₂ is hydrogen atom and R₃ ispyrrolidinyl (which may be substituted with hydroxy C₁-C₆ alkyl) when R₁is hydroxyl.
 2. The compound according to claim 1 wherein R₁ is chloro.3. The compound according to claim 1 wherein R₁ is chloro and R₂ isamino.
 4. The compound according to claim 1 wherein R₁ is chloro, R₂ isamino, R₃ is dimethylmorpholino, R₄ and R₅ each are hydrogen atom and Xis nitrogen atom.
 5. The compound according to claim 1 wherein R₁ ischloro and R₂ is hydroxyl.
 6. The compound according to claim 1 whereinR₁ is chloro, R₂ is hydroxyl, R₃ is morpholino, R₄ and R₅ each arehydrogen atom and X is nitrogen atom.
 7. The compound according to claim1 wherein R₁ is hydroxyl, R₂ is hydrogen atom and R₃ is pyrrolidinyl(which may be substituted with hydroxymethyl).
 8. The compound accordingto claim 1 wherein the compound represented by the formula I is2-(2-difluoromethyl-4-hydroxybenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholinopyrimidine,2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-(2,2-dimethylmorpholino)-6-morpholino-1,3,5-triazine,2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholino-1,3,5-triazine,2-(6-amino-4-chloro-2-difluoromethylbenzimidazol-1-yl)-4-[methyl(1-methylpiperidin-4-yl)amino]-6-morpholino-1,3,5-triazine,2-(2-difluoromethyl-4-hydroxybenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholino-1,3,5-triazineor2-(4-chloro-2-difluoromethyl-5-hydroxybenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine.9. The compound according to claim 1 wherein the compound represented bythe formula I is2-(2-difluoromethyl-4-hydroxybenzimidazol-1-yl)-4-(2-hydroxymethylpyrrolidin-1-yl)-6-morpholino-1,3,5-triazine.10. An antitumor agent comprising at least one of compounds as claimedin any of claims 1 to 9 as effective component.
 11. A pharmaceuticalcomposition including the compound as claimed in any of claims 1 to 9 asan antitumor active component together with pharmaceutically acceptablediluent or carrier.